1. Field of the Invention
The present invention relates to a structure for coupling a muffler for a linear compressor, and in particular to an improved structure for coupling a muffler for a linear compressor which is capable of implementing an easier fabrication, preventing a friction noise generated between elements when a piston reciprocates by obtaining a stable coupling between the elements, and preventing any deformation in the radial direction of a spring which elastically supports the piston and fixes a muffler to the piston.
2. Description of the Conventional Art
Generally, a compressor which forms a refrigerating cycle apparatus such as an evaporator, an accumulator, etc. includes a driving force generator, which is a machine for compressing gases such as air or refrigerant based on a rotation movement of a vane or a rotor or a reciprocating movement of a piston, for driving the vane, rotor, and piston, and a compression mechanism unit for sucking and compressing the gas based on the driving force transferred from the driving force generator.
The thusly constituted compressor is classified into a hermetic type and a separation type based on the installation type of the driving force generator and the compression mechanism unit. Of which, in the hermetic type, the driving force generator and the compression mechanism unit are installed in a predetermined shaped hermetic container, and in the separation type, the driving force generator is installed outside the hermetic container, so that a driving force generated by the driving force generator is applied to the compression mechanism unit in the hermetic container.
The hermetic type compressor is classified into a rotary type, a reciprocating type, a linear type and a scroll type in accordance with the structure for compressing gas. Recently, the user of the linear compressor is increased due to its characteristic that the piston is directly reciprocated using a magnet and coil without using a crank shaft in order to overcome various problems of the compressor which is designed to use the crank shaft.
As shown in FIG. 1, in the linear compressor, a hallow cylindrical inner casing 2 with its both ends being opened is installed in the interior of a hallow cylindrical hermetic container 1. A semi-circular cover 10 having a suction hole 10a formed at its center portion is covered at one end of the inner casing 2. A semicircular cover plate 3 having a through hole (not shown) formed at its center portion is covered at the other end of the inner casing 2. A cylindrical cylinder 4 is inserted into the through hole of the cover plate 3, and an exhaust valve assembly 13 and a head cover 14 are engaged to an end portion of the cylinder 4 for thereby discharging a compressed refrigerant gas.
In addition, in the interior of the inner casing is installed a linear motor comprising an outer lamination 5 fixed to an inner wall of the inner casing 2 in a circular form, a circular inner lamination 6 fixedly inserted into an outer surface of the cylinder 4, a hallow cylindrical first magnet paddle 7 with its both ends being disposed between the laminations 5 and 6, and a second magnet paddle 8 covering one end of the first magnet paddle 7. One end of the piston 9 is fixed at the center portion of the inner surface of the second magnet paddle 8 of the linear motor so that the same is reciprocated within the cylinder 4. When a power is supplied, the first magnet paddle 7 reciprocates between the laminations 5 and 6 at a high speed by the magnetic force induced between the laminations 5 and 6, so that the piston 9 is moved for thereby compressing the refrigerant gas sucked.
In addition, the piston 9 includes a cylindrical piston body 9a having a gas path F formed therein, and a support portion 9b extended from the end portion of the piston body 9a and having a predetermined area. A plurality of engaging holes (not shown) are formed at the support portion 9b, so that the piston 9 is engaged with the second magnet paddle 8 by an engaging bolt (not shown).
In addition, an inner side coil spring 11 is installed between an inner surface of the inner lamination 6 and an inner surface of the second magnet paddle 8, and an outer coil spring 12 is installed between an outer surface of the second magnet paddle 8 and an inner surface of the cover 10 for thereby elastically supporting the piston 9 when the piston 9 reciprocates within the cylinder 4 in association with the first and second magnet paddles of the linear motor for thereby generating and storing a kinetic energy.
Here, the support structure of the inner and outer side coil springs 11 and 12 will be explained.
As shown in FIG. 2, in the spring support structure for a conventional linear compressor, a first support plate 17 having a rim portion 17b perpendicularly curved to have an inner diameter corresponding to an outer diameter of the outer coil spring 12 at the rim portion of a circular plate portion 17a having a predetermined thickness is engaged at the inner side center portion of the cover 10. A second support plate 18 having a rim portion 18b perpendicularly curved to have an inner diameter larger than an outer diameter of the outer coil spring 12 at the rim portion of the circular plate portion 18a having a predetermined thickness is engaged at an outer surface of the second magnet paddle 8. A third support plate 19 having a rim potion 19b perpendicularly curved to have an inner diameter larger than an outer diameter of the inner coil spring 11 at the rim portion of the circular plate portion 19a having a predetermined thickness is engaged at the inner surface of the second magnet paddle 8. A fourth support plate 20 having a rim portion 20b perpendicularly curved to have an inner diameter corresponding to an outer diameter of the inner coil spring 11 at the rim portion of the circular plate having a predetermined thickness is engaged at a surface of the inner lamination 6. The outer coil spring 12 is disposed between the first support plate 17 and the second support plate 18. The inner coil spring 11 is disposed between the third support plate 19 and the fourth support plate for thereby elastically supporting the piston 9.
At this time, the outer coil spring 12 has its one end fixed to the first support plate 17 and its another end loosely supported by the second support plate 18. The inner coil spring 11 has its one end loosely supported by the third support plate 19, and its another end fixed to the fourth support plate 20.
In the drawings, reference numeral 16 represents an oil supply apparatus, and 1a represents a suction tube.
The operation of the conventional linear compressor will be explained with reference to the accompanying drawings.
Namely, in the conventional linear compressor, when a current is applied to the linear motor, a magnetic force is induced between the inner lamination 6 and the outer lamination 5. Therefore, the first magnet paddle 7 reciprocates between the laminations 5 and 6 at a high speed. The second magnet paddle 8 covering one end of the first magnet paddle 7 is activated, and the piston 9 connected with the inner center portion of the second magnet paddle 8 reciprocates within the interior of the cylinder 4. The refrigerant gas sucked into the hermetic container 1 is sucked into a compression space P of the cylinder 4 through the gas flow path F formed in the interior of the piston 9, and then is compressed therein. The thusly compressed gas is exhausted through the exhaust valve assembly 13 and the head cover 14.
At this time, the refrigerant gas introduced into the hermetic container 1 is fully filled into the interior of the hermetic container 1. When the piston 9 reciprocates, the gas is sucked into the compression space P formed in the interior of the cylinder 4 along the gas flow path F of the piston 9 and then is compressed and exhausted in the compression cycle of the piston 9. During the compression of the refrigerant gas, the exhaust valve assembly 13 is opened/closed by the pressure difference between the compression space P and the exhaust space D for thereby generating noises. The thusly generated noises are applied through the gas flow path F of the piston 9 and then spread to the outside of the inner casing 2 for thereby generating a compressor noise.
Therefore, in order to overcome the above-described noise problem, in the conventional linear compressor, a muffler is fixed based on a predetermined shape coupling structure for preventing the noise generated in the gas flow path of the piston 9.
As shown in FIG. 3, in the muffle coupling structure for a conventional linear compressor, a muffler 30 is disposed from the suction portion of the cover 10 to the gas flow path of the piston 9. End portions of the muffler 30 are fixed at the portions of the refrigerant gas suction portion 10a of the cover 10 for thereby preventing any movement of the same.
However, in the muffler coupling structure for a conventional linear compressor, an engaging member B and engaging hole (not shown) are additionally needed for coupling the muffler 30 to the cover 10 for thereby increasing the fabrication cost and the number of fabrication processes, so that the productivity is decreased.
In addition, since the inner and outer coil springs 11 and 12 elastically supporting the piston when the piston 9 reciprocates are loosely supported by the second and third support plates 18 and 19 formed on the inner and outer surfaces of the second magnet paddle 8, as shown in FIGS. 4A and 4B, a radial eccentric deformation may occur in the spring during the contracting and expanding process of the spring as the piston 9 reciprocates. Therefore, a rotation moment may occur in the piston 9 due to the eccentric deformation of the spring, so that a friction occurs between the inner surfaces of the piston 9 and the cylinder 4 resulting in an abrasion between the friction elements.